1. Technical Field
The present disclosure relates to apparatuses and methods for manufacturing a printed circuit board (PCB), and more particularly relates to an apparatus for activating a layer of glue on a PCB and a method using the same.
2. Description of Related Art
Many circuit boards comprise a substrate having a pattern of copper conductive tracks formed onto it. The substrate can either be rigid, or flexible. Active and passive electronic components are soldered onto the board via a set of pads arranged around the periphery of a component site.
In a manufacturing process for a PCB, the copper conductive tracks may be protected from oxidation by coating the circuit board with a film of material. The film includes an insulation layer such as polyimide, and an adhesive layer. The adhesive layer is arranged between the circuit board and the insulation layer. A pressing apparatus comprising an upper hot press plate, and a lower hot press plate is provided. The film is positioned between the upper and lower hot press plates, and then the adhesive layer is melted by the upper and lower hot press plates. Then the lower hot press plate is pushed by a cylinder rod to move close to the upper hot press plate, so as to press the film and the circuit board firmly together. Finally, the adhesive is cured, thereby forming a PCB protected from oxidation. The end of the cylinder rod just contacts the center portion of the lower hot press plate, thus the pressure applied to the center portion of the film is greater than that applied to the surrounding region. Thus some melted material of the adhesive layer will stream from the center region to the surrounding portion, which causes a non-uniform thickness of the adhesive layer. In addition, the surrounding region with dense conductive tracks may not be totally covered or filled with the adhesive material of the adhesive layer because of differences in pressure, thereby forming bubbles on the PCB. Too many bubbles may cause bad adhesion between the circuit board and the protective film.
What is needed, therefore, is an apparatus for more reliably pressing a PCB and a method using the same.